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Henning Heldbjerg

Rare case of an adult male Montagu's Harrier Circus pygargus over-summering in West Africa, as revealed by GPS tracking

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  • Iben H. Sorensen, Danish Hunters Assoc
  • ,
  • Almut E. Schlaich, University Medical Center Groningen, UMCG, Groningen, Holland
  • ,
  • Raymond H. G. Klaassen, University Medical Center Groningen, UMCG, Groningen, Holland
  • ,
  • Henning Heldbjerg
  • Ben J. Koks, Dutch Montagus Harrier Fdn

Over-summering within or near the African wintering range by immature, non-breeding individuals occurs regularly in several species of long-distance migratory raptors, yet the extent of over-summering in Africa by adult birds remains unclear. In this study, we describe a case of an adult Montagu's Harrier over-summering in Africa, as revealed by GPS tracking. By relating detailed knowledge of the bird's movements to remotely sensed environmental data (normalized difference vegetation index, NDVI), we show that over-summering in this case was likely related to an exceptionally difficult breeding season the previous year rather than an effect of adverse weather conditions encountered during the winter or a failed attempt to migrate. Various factors are discussed as potential driving forces behind the bird's intra-African movements. Finally, we relate the documented case to a large number of North European Montagu's Harriers studied by telemetry and show that over-summering in Africa by adult individuals is indeed a rare event.

TidsskriftJournal of Ornithology
Sider (fra-til)753-760
Antal sider8
StatusUdgivet - jul. 2017

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